The present invention relates to an RF shielding method, an MRI (Magnetic Resonance Imaging) apparatus, and a transmitting/receiving surface coil. More particularly, the present invention is concerned with an RF shielding method, an MRI apparatus, and a transmitting/receiving surface coil, which can reduce the cost for isolation of a body coil installed on a magnet assembly side, from a surface coil.
Heretofore, there has been known a technique wherein an RF shield is provided between a body coil installed on a magnet assembly side and a gradient magnetic field coil (see, for example, Patent Literatures 1 and 2).
[Patent Literature 1] Japanese Unexamined Patent Publication No. 2000-11619
[Patent Literature 2] Japanese Unexamined Patent Publication No. 2004-248928
Heretofore, isolation of a gradient magnetic field coil against RF pulses transmitted from a body coil installed on a magnet assembly side has been performed through an RF shield, but isolation of a body coil installed on a magnet assembly side against RF pulses transmitted from a surface coil has been performed using a switch provided on the body coil side to switch ON/OFF condition of a diode from one to the other through a bias power supply and thereby turn ON or OFF the body coil.
However, the bias power supply is of a large current or large voltage specification and a high performance filter for the prevention of noise propagation is required, thus resulting in an increase of the apparatus scale and of cost. Besides, for the switch provided on the body coil side, it is necessary to use a component resistant to high current and high voltage such as a diode for a large current, thus also giving rise to the problem that the cost becomes high.